Finding the impedance of a circuit

In summary, the conversation discusses different approaches to finding the impedance between two nodes in a circuit. The initial attempt was to find the impedance of the 5 mH inductor, but that did not work. Then, the Thevenin Theorem was suggested, but another method of finding the impedance of the parallel combination between nodes b and g was recommended instead. Ultimately, the impedance of the three branches in parallel between nodes a and g needs to be calculated. It is also noted that no power source is present, making Thevenin unnecessary.
  • #1
jesuslovesu
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Homework Statement


http://img297.imageshack.us/img297/2951/picqk5.th.jpg

I'm just trying to do part a for the moment.

Homework Equations





The Attempt at a Solution



My initial attempt was just trying to find the impedance of the 5 mH inductor and saying that would be Zin. Unfortunately that doesn't seem to be the case.

Then I tried doing a thevenin type problem where I find the impedance of all the elements to the right of the inductor, but that doesn't seem to work either.

I also just tried finding Zeq for the whole thing but that doesn't work either, hmm.
How does one find the impedance between two nodes? I would have thought that the 2nd method would have worked for sure.
 
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  • #2
Thevenin Theorem should work here. Find the equivalent impedance seen from the nodes a and g.

(Hint : Fold from the right side to the left side)
 
  • #3
No need to use Thevenin, since there is no power source.
Between nodes b and g there are two elements. Find the impedance of the parallel combination. Between nodes a and b there is a capacitor, that is in series with the impedance bg. Finally, calculate the impedance of the three branches in parallel between nodes a and g.
A similar reasoning can be made for items b and c.
 

1. What is impedance?

Impedance is the measure of the opposition that a circuit presents to the flow of alternating current (AC). It is a combination of resistance, inductance, and capacitance in a circuit.

2. Why is it important to find the impedance of a circuit?

Knowing the impedance of a circuit is important because it helps us understand how the circuit will behave when an AC current is applied. It also allows us to calculate the current and voltage in the circuit and determine its power and efficiency.

3. How is impedance different from resistance?

Impedance is different from resistance because it takes into account not only the resistance of a circuit but also its inductance and capacitance. Resistance only considers the opposition to the flow of direct current (DC).

4. How do you calculate the impedance of a circuit?

The impedance of a circuit can be calculated using Ohm's law, which states that impedance (Z) is equal to the voltage (V) divided by the current (I). It can also be calculated using the formula Z = √(R² + (XL - XC)²), where R is the resistance, XL is the inductive reactance, and XC is the capacitive reactance.

5. What are some common units of measurement for impedance?

The most common units of measurement for impedance are ohms (Ω) and siemens (S). Ohms are used to measure the resistance component of impedance, while siemens are used to measure the inductive and capacitive components of impedance.

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